diff options
| author |   djm <djm@openbsd.org> | 2008-12-29 22:25:50 +0000 |
|---|---|---|
| committer | djm <djm@openbsd.org> | 2008-12-29 22:25:50 +0000 |
| commit | c97a2171e4d82f7ef8c064e97426bb5df7bf2993 (patch) | |
| tree | fbe4970d1ee6c0aac3dd743a6908932bdf113136 /lib/libc/stdlib/malloc.3 | |
| parent | Give ifb its own display type (be sure to make includes before rebuilding (diff) | |
| download | wireguard-openbsd-c97a2171e4d82f7ef8c064e97426bb5df7bf2993.tar.xz wireguard-openbsd-c97a2171e4d82f7ef8c064e97426bb5df7bf2993.zip | |
extra paranoia for malloc(3):
Move all runtime options into a structure that is made read-only
(via mprotect) after initialisation to protect against attacks that
overwrite options to turn off malloc protections (e.g. use-after-free)
Allocate the main bookkeeping data (struct dir_info) using mmap(),
thereby giving it an unpredictable address. Place a PROT_NONE guard
page on either side to further frustrate attacks on it.
Add a new 'L' option that maps struct dir_info PROT_NONE except when
in the allocator code itself. Makes attacks on it basically impossible.
feedback tedu deraadt otto canacar
ok otto
Diffstat (limited to 'lib/libc/stdlib/malloc.3')
| -rw-r--r-- | lib/libc/stdlib/malloc.3 | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3 index edcd748ed97..2458834302f 100644 --- a/lib/libc/stdlib/malloc.3 +++ b/lib/libc/stdlib/malloc.3 @@ -30,9 +30,9 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.\" $OpenBSD: malloc.3,v 1.58 2008/11/26 12:06:54 pedro Exp $ +.\" $OpenBSD: malloc.3,v 1.59 2008/12/29 22:25:50 djm Exp $ .\" -.Dd $Mdocdate: November 26 2008 $ +.Dd $Mdocdate: December 29 2008 $ .Dt MALLOC 3 .Os .Sh NAME @@ -249,6 +249,13 @@ Currently junk is bytes of 0xd0 when allocating; this is pronounced .Dq Duh . \&:-) Freed chunks are filled with 0xdf. +.It Cm L +.Dq Lock . +Lock critical data structures using +.Xr mprotect 2 +to protect against modification except by +.Nm +and related routines. .It Cm P .Dq Move allocations within a page. Allocations larger than half a page but smaller than a page |